1. Field of the Invention
The present invention relates generally to electrostatic discharge protection and over-current protection of electronic devices, and more specifically, to the use of silicon germanium (SiGe) devices functioning as ESD circuit elements for protecting electronic I/O circuits.
2. Discussion of the Prior Art
Electrostatic discharge protection in BiCMOS or CMOS electronic devices typically utilize resistive elements, e.g., resistors. However, the resistor elements used in BiCMOS or CMOS exhibit linear resistance characteristics and do not demonstrate strong velocity saturation (Kirk) effect, i.e., a high resistance state that is significantly above a linear resistance portion of the device""s current-voltage curve. Consequently, these types of resistive elements may be suitable for applications in limited current/voltage ranges and consequently, limited types of ESD and I/O circuit applications.
It would be highly desirable to provide a device that exhibits a strong velocity saturation effect, i.e., a high dynamic-on resistance and that may be exploited to provide resistance buffering, and resistor ballasting of I/O networks and ESD networks.
It would additionally be highly desirable to provide a SiGe device dimensioned to exhibit a strong velocity saturation (Kirk) effect, to provide resistance buffering, and resistor ballasting of I/O networks and ESD networks.
It is an object of the invention to provide a SiGe transistor device dimensioned to exhibit a strong velocity saturation (Kirk) effect, and configured to provide resistance buffering, and resistor ballasting of I/O networks and ESD networks.
It is another object of the invention to provide a SiGe transistor in a diodic configuration to provide resistance buffering, and resistor ballasting of I/O networks and ESD networks, utilizing the Kirk effect velocity saturation.
According to the invention, there is provided an SiGe device configured to exhibit high velocity saturation resistance characteristic for buffering large voltages at low currents, wherein for circuit applications, the SiGe device is connected in series with a circuit element for protection of the circuit element. Advantageously, the device may be exploited as a buffer element providing ESD circuit protection for receiver devices, power supply clamp circuits and I/O driver circuits.